Punctuality Statistics Notes
|Data Month||Date Available On Website|
1. These figures are compiled by the Civil Aviation Authority with the co-operation of airports and Airport Coordination Ltd.
2. The figures cover both arrivals and departures aggregated, except in the case of the Full Analysis with Arrival – Departure Split. In this table, arrivals and departures are stated separately.
3. Actual times of operation are derived from the flight by flight air transport movement returns made by airports to the CAA. The planned times supplied by Airport Coordination Ltd include changes made up to 30 minutes before operation.
4. Only obvious mismatches between the two sources have been reconciled.
5. When the two sets of data are matched, if an airline appears to operate a series of flights significantly “off slot”, the CAA will substitute information from published timetables (where such are available) in place of the ACL slot data.
6. Prior to April 1998, Luton planned times of operation were taken from daily flight plans provided by the airport. These were completed before the week in question and, therefore, did not reflect any changes to the plan made at short notice.
7. The number of unmatched actual flights represented those air transport movements which actually took place at the airport but for which no corresponding planned flight was found. The reasons for this would normally be: (a) the flight was a diversion from another airport; (b) the flight was not recorded with Airport Coordination Ltd or airport (see notes 4 and 5); (c) the flight was a short-haul flight more than one hour before the planned time; (d) the flight was planned to take place in the previous month; (e) the plan or the air transport movement record contained an incorrectly reported item of data causing the flight not to match.
8. The number of unmatched planned flights represents those Airport Coordination Ltd or airport flights planned (see notes 4 and 5) for which a corresponding Air Transport Movement return has not been found. The reasons for these would normally be: (a) the flight was diverted to another airport; (b) the flight was cancelled; (c) the planned time was for a short haul flight more than one hour after the flight; (d) the flight took place in the following month; (e) either the plan or the air transport movement record contained an incorrectly reported item of data causing it not to match.
9. Because the planned time of operation relates to the arrival/departure at the stand, whilst the actual time of operation relates to wheels on/off the runway, the following taxi time assumptions have been built in following information provided by Airport Coordination Ltd or the airport. A general review of taxi times was undertaken during 2008 and the amended values were implemented with effect from January 2009. For comparison purposes 2008 data, shown in 2009 tables, have been recalculated using new taxi times.
|Departures||17 minutes||(i), (ii)|
|London City||Arrivals||3 minutes|
(i) No account is taken of the different taxi-ing times associated with the terminal building used.
(ii) Prior to October 2003, Gatwick recorded the departure time from the stand.
(iii) Birmingham Airport record actual time of operation as arrival / departure at the stand.
10. With effect from January 2000 data month, early flights are set to zero delay. Prior to this, an early flight will show a negative delay. This will affect the ‘average delay’ column. Average delays from January 2000 onwards should not be compared to average delays prior to January 2000. Tables for January to December 2000 inclusive do not include columns relating to the corresponding month the previous year for this reason. These tables should also not be compared with previously published tables.
11. Routes – airline combinations are shown where there is more than one matched flight. Any lines omitted for this reason will still be included in total figures however. For this reason, the totals shown may not always exactly match the data in the table.
12. All-cargo services and air taxi services are excluded from the analysis.
13. The characteristics of scheduled and charter modes are different. For example, scheduled and charter flights tend to operate to different destinations at different times of the day and week. Because of this and the exclusion of cancellations from the data, simplistic comparisons between the two modes should be avoided.